Marker-plus-reader-based authentication systems can be used to distinguish authentic from counterfeit items. The authentication is based on detecting the presence of secret markers in authentic items with special readers. The reader responds to the detected presence of the secret markers by giving a pass/fail indication. It is important that the reader (authentication device) does not fall into unauthorized possession because its pass/fail functionality can be exploited to manufacture a replicated security feature on the counterfeit item.
It is useful therefore to have a means of enabling the authentication device that cannot be realized by possessing the authentication device alone. Such an enabling means could be, for example, a key or password. However, the corresponding lock or password request on the authentication device could make apparent such a security mechanism and a counterfeiter would attempt to disable the lock or password mechanism.
Because there are ongoing efforts to counterfeit goods and to circumvent the efficacy of counterfeit detection systems, an authentication device with improved security is desirable.